Taper fiber is a kind of fiber with variational diameter along the longitudinal direction.The couple mode equations of fiber Bragg grating (FBG) based on fused taper fiber are solved by numerical method of broyden and shooting,and the effect of taper along the longitudinal direction on spectrum of FBG is analysed.The results show that the spectrum of FBG shifts to short wavelength and the bandwidth broadens because of the effect of taper compared with the condition of uniform FBG. The peak reflectivity and the transmission reduce because the ability of restricting optical power of the fiber core becomes weak.The phenomena become more obvious as the taper becomes bigger.Taper fibers are fabricated by fused taper method,and different taper fibers are obtained through changing the motor velocity on the basis of the same fused taper length. The relation between motor velocity and the loss of the taper fiber is analysed. A Bragg grating is written in taper fiber with 248 nm ultraviolet laser and uniform phase mask of 537 nm,then the effect of different tapers on the spectrum is analysed. The experimental results are consistent with the theoretical results.